Eiko Masuyama was a celebrated Japanese voice actress and narrator, renowned for originating some of anime's most iconic female characters. Born Tomoko Masada on April 22, 1936, in Tokyo, she was the youngest of four sisters. As a child, she spoke slowly, and a teacher's comment about her speech led her to join a children's theater company at age 12 to improve. There, she studied under Miyoko Asō, overcame her insecurities, and developed an interest in acting. After transitioning to voice acting in the 1960s, she joined Aoni Production, finding the schedule more flexible for balancing work and childcare. She remained with the agency for the rest of her career.

Masuyama's career was defined by several legendary roles. She is most famously known as the second voice of the femme fatale Fujiko Mine in the Lupin III series, a role she held from 1977's TV second series until 2010. However, her connection to the character began earlier; she had voiced Fujiko in the 1969 and 1970 pilot films for the anime. Over the decades, she reprised the role in numerous TV specials and films, such as Lupin III: Dragon of Doom, Lupin III: Island of Assassins, Lupin III: Crisis in Tokyo, Lupin III: Farewell to Nostradamus, and many more. In 1973, she voiced the titular transforming heroine in the original Cutie Honey, creating the role of Honey Kisaragi. She also became the long-serving voice of the perpetually optimistic mother in the long-running Tensai Bakabon (天才バカボン) series across its various iterations, including Ganso Tensai Bakabon, Heisei Tensai Bakabon, and Rerere no Tensai Bakabon. Another notable recurring role was as Sumire Hoshino, the female member of the superhero team known as Perko or Perman No. 3, in the 1983 Perman anime and its subsequent films.

Beyond these signature parts, her extensive filmography included a wide array of characters. She played Joan Randall in Captain Future, provided narration for Tongari Bōshi no Memoru, and voiced roles in classics like Attack No. 1 (as Midori Hayakawa and Sherenina), Dogtanian and the Three Muskehounds (as Milady), and Andersen Monogatari (as Chianti). Her work also extended to foreign dubbing, where she was the regular Japanese voice for actress Lee Remick and dubbed characters like Melody Valentine in Josie and the Pussycats and Baroness Elsa von Schraeder in The Sound of Music.

Throughout her long career, Masuyama was a staple at Aoni Production, frequently collaborating with other voice acting legends. In her later years, she focused more on narration work but would occasionally reprise her most famous roles. Her immense contributions to the industry were recognized with the Anime Outreach Category award at the 2017 Tokyo Anime Award Festival and the Merit Award at the 15th Seiyu Awards in 2021.

Eiko Masuyama passed away from pneumonia on May 20, 2024, at the age of 88. Her death marked the end of an era, as she was the last surviving member of the main cast from the heyday of the Lupin III series. She left behind a legacy as one of the foundational voices of Japanese animation, having brought to life characters that continue to inspire fans and fellow voice actors alike.